Booster catch has been done as has booster re-flight. The only remaining part of the full functionality that has not been proven out is ship reuse.

I see.

"The booster’s primary objective on Flight 15 will be executing a successful launch, ascent, stage separation, boostback burn, and return to the launch site for catch. This will be the first return and catch attempt for a Super Heavy V3 booster." [1]

[1] https://www.spacex.com/launches/starship-flight-15